This R01 application seeks support to conduct a large national study that will comprehensively identify the impact of state level autism-related policies on the publicly funded healthcare utilization of children with autism spectrum disorders (ASD). The three primary aims of the study are to 1) conduct an intensive examination of state policies and practices that may affect Medicaid-reimbursed healthcare delivery to children with ASD;2) provide accurate national and state-level estimates of publicly-funded healthcare utilization among children with ASD;and 3) examine the relative contribution of demographic, clinical and system-of-care characteristics on the types, intensity and patterns of related service use. To accomplish these aims, we will review and code all relevant state-level policy documents to define the publicly funded healthcare service delivery system for ASD in each state. We will supplement this census through interviews with state administrators responsible for ASD-related health services. This most recent year of available Medicaid claims will be used to measure service utilization and associated expenditures at the national and state levels. We will then examine the independent associations of state policies, and school district, family and child characteristics with service utilization. These findings will provide critical information to states as they develop appropriate standards of care and related policies for the growing number of children diagnosed with ASD, and will potentially lead to policy models that improve care. This study will set the stage for future studies in which service utilization data from other systems and primary data about families'experiences and outcomes are linked to data on healthcare. The study also will provide a baseline against which to measure the effects of future system-level interventions. Finally, the results will provide evidence for a conceptual framework for understanding how states address the needs of children with chronic disabilities in which the best course of treatment and expected outcomes are uncertain.